Printing telegraph system



Nov. 23, 1943. J. a. MOORE ETAL Re. 22,394

PRINTING TELEGRAPH SYSTEM Original Filed May '7, 1936 2 Sheets-Sheet 1rlNVENTORS JOHN B. MOORE mcn o E. MATHES- ATTORNEY NW. 23, 1943. MOORERe. 22,394

PRINTING TELEGRAPH SYSTEM Origina I Filed May '1, 19:56 2 Sheets-Sheet 2INVENTORS 1 JOHN B. Moon;

RIC 2 E. MATHES ATTORNEY Reissued Nov. 23, 1943 a Re. 22,394

PRINTING TELEGRAPH SYSTEM John B. Moore, Brooklyn, N. 1., and Richard E.Mathes, Westfleld, N. J asslgnors to Radio Corporation of America, acorporation of Delaware Original No. 2,183,147, dated December 12, 1939,Serial No. 78,348, May 7, 1936. Renewed April 19, 1939. Application forreissue August 28, 1942, Serial No. 456,514

23' Claims.

This invention relates to printing telegraph systems and moreparticularly to a system in which the circuits are subject to staticinterference and fading conditions.

Printing telegraph apparatus of the more generally used types employfive time elements for coding the signals representing each character tobe printed.' If these signals are sent over a radio channel or a carrierwave conductor channel they are very much subject to distortion andfading .or to mutilation due to the presence of static impulses. Thecode signals, therefore, are liable to be received in an unintelligibleform.

Accordingly, it is an object of our invention to provide a new method ofcode signaling for operatlon of printing telegraph equipment. It is' afurther object of our invention to provide the means for so actuating aprinter in response to code signals that the correct characters will beprinted so long as the signals are not mutilated, but that when a signalis mutilated by static or fading, then a misprint will be prevented.

It is aafurther object of our invention to provide means for causing theprinter to produce an error indication if any character signal becomesunduly distorted or mutilated. I

In carrying out our invention we propose to utilize a signaling codewhichin all cases comprises a uniform number of marking impulses. Thus,if fewer or more than the correct number of impulses for characterselection is received, the master selector device at the receiver willlock out the printing mechanism and thereby preventthe printing or anincorrect character. In place of the character that would be incorrect-1y printed we can operate the master selector so as to cause an errorindicating type bar to be actuated.

If instead of a five-unit code, we adopt a sevenunit code. taking eitherthree or tour of the seven elements at a time as marking pulses, it ispossible to obtain thirty-five combinations: By the use of eight timeelements, taking four at a time as marking pulses for each combination,there is available a total of seventy combinations. By taking only threeat a time of the eight time cle ments a total of fifty-six combinationsis available.

Our invention will be described in more detail upon. reference to theaccompanying drawings,

'inwhich Figures 1 and 2 are code charts showing a specific arrangementof marking and spacing of a printing telegraph receiver to be actuated.

Fig. 3 shows in perspective certain details of a printer including themasterselector bars and a few. of the type bar selectors of which one isa selector for an error indicating type bar; Means 'are also shown forcausing the printing mechanism to be locked out and the error indicatingtype bar to be selected when more Or less than the proper number ofmarking impulses is received: and

Fig. 4 shows a circuit diagram of a modification of our inventionwherein relays are used in place of step-by-step mechanical apparatusfor obtaining the selection of the error indicating type bar whenneeded.

The Baudct code which is in general use in printing telegraph systems iscomposed of live permutational time elements in any one of which amarking or spacing impulse may be transmitted. The, charactersignificance of each code signal is determined by the order of sequenceof the marking and spacing impulses. In synchronous systems a continuoussuccession of five-unit code signals is transmitted. In the so-calledstartstop systems, however, a spacing impulse of fixed duration isutilized to start the printer in operation'for selecting eachtransmitted character to be printed. This spacing impulse is immediatelyfollowed by the five-unit code signal and then comes a stop-impulse" ofindefinite duration to arrest the printer operation until another typekey on the keyboard is depressed. In the description to follow it willbe understood that the marking and spacing impulses requlredforcharacter selection are the only ones to be herein considered since theuse of additional impulses for operation of a printer by the start-stopmethod is optional and our invention may be applied to a start-stopsystem as well as to a synchronous system. There are thirty-two possiblecombinations of marking and spacing impulses in the fiveunit codearrangement. That code makes maxi.-

I mum use 01' the circuit time and of the frequency time elementssuitable for selecting the type bars band of a radio communicationschannel. It is, however, only suitable for use on a circuit which isfree from interference. Fading or noise of any kind results in errors inthe received copy. Its use on radio circuits is, therefore, relativelylimited. Another-disadvantage of the five-unit code is that the numberof combinations available is not suflicient to print all of thecharacters desired including letters, figures, punctuation marks, etc.Accordingly, it is the practice .to employ a shift mechanism. It caneasily happen that static impulses will produce s eh a code sig-- nal asto improperly actuate the sh t mechanism at the receiving end when thetransmitting machine isstlll unshlfted. The intelligence thus ,becomesgarbled even without the knowledge of l the transmitting operator.

c The arrangement of marking and spacing impulses as shown in Fig. 1 maybe considered from the standpoint that it is suitable either for aseven-unit code or for a portion of an eight-unit code. For a seven-unitcode the marking and spacing units may be according to the showing inthe first seven columns. For an eight-unit code, the marking and spacingunits may be as designated in the eight columns of both Fig. 1

actuated for selecting a character to be typed. Theescapeme'nt wheel 8has, therefore, rotated three steps from its initial position. It mustbe ,understood, however, that these three steps will and Fig. 2. In thiscase it would usually be unnecessary to employ'any code signals forshift and, unshift as shown in Fig. 1.

It will be noted that in the embodiment of our invention suggested byFigs. 1 and 2 every signal is composed of three marking impulses butthese marking impulses are differently arranged with spacing impulsesinterspersed. It is equally possible that four marking impulses might beused with the remaining portion of each equal length code signal filledin by spacing impulses. It is also equally possible that a signallingcode might be adopted in which each signal is comarranged in diflerentcombinations.

be taken regardless of which particular code bars 5 are actuated,although in the illustration,

it is shown that the first three of these code bars viewed from thefront of the device have been actuated. During the rotation of theescapement wheel fi'a cam H has been rotated through a like are so, thata notch 18 in the face of this cam has come into alignment with a ridermem-- her I! mounted on the end or the error indicating selector bar 25.This bar 20 has accord- J ingly been pulled slightly to the left underthe traction of the spring 2|. In this position the selector bar 22corresponding with the'error indicating type bar has been restrainedfrom dropping into the guide notches 23 of the code selector bars 5 byvirtue of a raised portion 24 adjacent the notch N on the errorselecting bar 20. In the code bars 5 the notches are purposely madewider than some of the other. notches in these bars in order that theselection of the cross bar 22 may be effected solely in response to theactuation of the error bar 20.

One of the type barselectors to has been shown in the figure as havingbeenlowered into Referring now. togFig. 3, we show one embodi-f ment of'thereceiving apparatus which is suitnai. Only those portions of aprinting'telegraph instrument are shown which relate to the invention.

The master selector. includes the conventional code selector bars 5 overwhich are the type character selector bars 5. During the reception of acode signal any three of the bars 5 may be moved longitudinally to theleft so as to bring into alignment certain notches I into which aselected cross bar 8 may drop. Only when the proper number of impulsesis received during the time taken upby a seven-unit code signal will atype bar selector 5 be permitted to drop into these aligned notches. Ifmore or fewer than three impulses are received, the cross bars 6 .will.all of them, beheld upby the raised portions or the selector bars 5. Inorder: to actuate an error indicating type bar. we have provided acounting device tobe controlled by the successive actuations of themaster selector code bars 5. This counting device includes anescapement; wheel 8, mounted on a shaft 9 and permitted to rotatestep-bystep when released by the escapement pawl either in response to adeficiency or an excess in mechanism M which is pivoted on therock-shaft H and is caused to oscillate by virtue of a cross bar l2which engages with raised teeth I: on the code selector bars 5.

A coiled spring ll tends to unwind. and to.

rotate the escapement wheel 8 in a counterclockwise direction with eachrelease of one or its teeth from engagement with the escapement pawl ID.The escapement wheel is prevented from over-riding successive steps bythe down-f ward movement'of the pawl member I5 into the aps betweentheescapement wheel teeth. After each movement of one of the code selectorbars 5 the escapement pawls l0. and 15 are returned to their normalpositionunder the tensionor the in Fig. ,3 have able for use withcode'systems having a fixed number of marking units in each charactersigthe notches of 'the code bars 5 where these notches'wer'e broughtinto alignment by the actuation of the first three of these bars and bynot actuating the remaining'four bars. If one of these four remainingbars had been actuatedthe escapement wheel would have taken a fourthstep. None of the type barai'or' the printing of intelligence could beactuated in this case but in order to distinguish between the mission ofa character due to a; faulty signal and anor- 'mal space between words,theerror indicating type bar is preferablyfactuated by the mechanismshown. This actuation can take place the number of marking impulses inthe code. Assume, for example that the number of im' pulses was only twoinstead of three. In this case the notch is in the'cam I! would not bein alignment with the rider member l9 and, therefore, the-notch N wouldbeexa'ctly under the bar 22 permitting it to be lowered the same as forthe selection of any normal printing character. i

In order to restore the escapement wheel 8 to its normal position uponcompletion of any printing operation, we preferably provide a rack andpinion mechanism connected in any suitable manner with the drivingmechanism for the printer; The rack bar 25 has been. shown in thedrawings as in its. normal position, ready tomake' a restoring movement.gitudinal, of the bar and during its stroke to the left. it engages withthe pinion 22 rotating the same clockwise so as to wind up the spring N.

The pinion 22 is loosely mounted upon the shaft 9 in order that itsrotative movements may always be through the same arc regardless oi thenumber of steps by which the escapement wheel 8 has been released, If anerror has been detected by' the reception-o! tour or more impulses when.three 'inipulses were normal, then the pinion 22 and the shaft 9 willbe rotated through alike are in response to the full strokeof therestoring bar 25. If, however, the escapement wheel 8 has taken fewerthan four steps, then while the pinion 22 is rotated'through its fullare for a restoring operation, it williir bring- This movement is lontheescapement wheel 3 back to its normal initial position, that is, withtooth designated "6 held by the escapement pawl I3, and with the pin 21resting against a stop 23. Further rotation of the pinion 22 will resultin winding up the spiral spring 26 which is stiffer than the spring [4.

Upon completion of the stroke of the restoring,

bar 25 a pin 29 which has ridden over the top of the guide member 33'isnow depressed into a' channel below this guide member 33 under controlof a Spring 3|. This disengages the rack from the pinion 22 and if thespring 26 isunder tension it will immediately unwind so as to repositionthe pinion 22 in normal relation to the shaft 9; that is, with the twostop pins 32 and 33" pressing one against the other. The pin 32, ismounted on the shaft 9 while the pin 33 is mounted on the pinion 22. Thenormal engagement of these pins one with the other is maintained undertension of the Spring 26.

Upon completing the return stroke of the restoring bar 25, the pin 29mounted thereon is lifted out of the channelbeneath the guide member 33by virtue of a resilient spring 34. This actuation of the restoring bar25 will be understood to take place coincidently with the printing atleast four impulses are received duringthe transmission of a codesignal, then further operations of the escapement member Ill-I will haveno effect in releasing the escapement wheel 8' because after-four stepsthe shaft. 9 will be arrested from further rotation due to theengagement of its pin 21 with the abutment member 35.

The number of teeth in the rackbar 25'is, therefore, limited to what arenecessary for rotating the pinion 22, the shaft 9 and the escapementwheel 8 through the arc subtended by four teeth on the escapement wheel.

' impulse.

In certain instances it may be found preferable .1

to employ a counting mechanism which comprises a system of relays as asubstitute for the escapement wheel andv escapement pawl mechanism shownin Fig. 3. Reference will, therefore, be now madeto Fig. 4 in which suchan electrical relay system has been shown diagrammatically.

In Figs. 3 and 4 corresponding parts, or parts possessing substantiallythe same functions, have been given like reference characters. 'In Fig.4, for example, the code selector bars 5 have been similarly shown'withteeth I3 and with notches 1 for selecting the type selecting cross bars6. In, this case, however, instead of actuating escapement pawls likethose, I, I5, shown in Fig. 3, the teeth I3 are caused to lift a lever36 against .the pressure of a spring 31. This action takes place witheach successive movement of the code bars 5. Contact is thereby madebetween the contact springs 33 so as to momentarily close a circuit froma source of potential 39 through different relays which are-actuated insuccession. Commencing. with the first stroke of a code bar 5, an

impulse is initiated from the source through the contacts 38, througharmature 42 and back 'contact 4| of relay 44, and thence through relayfrom the battery 39 through circuit breaking contacts 45, relay 44,contacts 43, relay 49, and thence to ground. Current flows through thiscircuit immediately upon the opening of contacts 33, but not before,because duringthe operation of impulsing, which takes place whenthelever 36 rides over a tooth [3, both terminals of the relay 44 are atthe same potential. When relay 44 is energized the contacts 43 causerelay 40 to be locked up. Also the armature 42 of relay 44 is pulledaway from the back contact 4| and into engagement with the front contact46. This prepares relay 41 for actuation in response to the second Thesecond impulse may, therefore, be traced from battery 39, throughcontacts 33,

armature 42, contact46, armature 50, contact 49, relay 4! and thence toground. Upon the completion of this impulse and the opening ofcontacts38, relay 4! locks up due to the closing of its contacts 5| andthe establishment of a locking circuit from battery 39 through contacts45 and relay 52. Upon the pulling up of the armature 56,

a circuit is now prepared through the front con-' tact 53 and thence tothe armature 54 of relay 55. The third impulse initiated at contacts 38may thenbe further traced through back contact 59 of 'relay 55 and relay5'! to ground. When relay 55 is actuated in response to the opening ofthe contacts 38 and the closing of the locking contacts 60 a circuit isestablished from battery 39 through circuit breaking contacts 45 and"the serially connected relays 55 and 51.

Relay 55 has two armatures 54 and 63 both of which are pulled upsimultaneously upon the breaking of the impulsing circuit at thecontacts 33. Armature, 54 upon contacting with the front contact Hprepares a circuit for a possible fourth -or any subsequent impulsethrough relay 61. Armature 63- upon contacting with its frontcontact '64feeds current from the battery 39 through circuit breaking contacts 45,contacts 64 and 53 and thence through a magnet 62 to ground. Thefunction of magnet 62 is to pull up its armature lever 65 to which isconnected the error bar 26. In the embodiment of our invention shown inFig. 4, the error bar 29 is normally held in position for selecting thetype bar 22 having an error indicating character thereon. It is onlywhen a character selection'consists of three marking imbeactuated by astatic impulse so as to mutilate the code signal, then the impulseproduced at the fourth time of closing the contacts 38 will be directedthrough the armature 42, front contact 46, armature 53, front-contact53, armature 54, front contact H and thenceto the relay 61 which 'isgrounded. This relay immediately locks up through the closing ofcontacts 12 and simultane-,

ously it breaks connectionbetween the'contacts 53 which are disposed inthe energizing circuit for the magnet 62. 43, 44, 41, 52, 51, 55 and 61are locked up, magnet 62 becomes de-energized and permits 01 the selec--tion of theerror indicating type bar 22, the same as when only one ortwo impulses of the seven-.

unit code signal had been received.

Simultaneously with the printingof a cliaracfter the restoring bar 25 ismechanically a t at Now although all of the'relays.

"Ihe mechanism for, doing this has not been shown I because it :is wellwithin the scope of, an ordinary mechanic to provide it. The c cultbreaking contacts 45 are, therefore, opened or the purpose of unlockingall of the relays which had been successively actuated during thecountin operation, The relay system is thus prepared for counting theimpulses of a succeeding code signal. a

We claim:

sponsive to character representing signals all of which signals are ofequal length and possess a fixed ratio other than one-to-one between thenumber of marking and spacing units thereof, -means to de-code saidsignals, and actuating mechanism, responsive to'the operation of saidcontrol of said de-coding means for effecting 'an error-key selectionupon receipt of a mutilated signal.

8. In a device of the class described, "printing mechanism-operable inresponse to the receipt of code signals having a uniform number ofmarking elements and a uniform number-of spacing elements, anerror-designating key, and means for 1. In a printing telegraph system,means rede-coding means to print a designated character only when asignal is received the marking and spacing units of which are inconformity with said fixed ratio.

2. In a printing telegraph system a'plurality of type bar selectors,means including a plurality of decoding elements cooperative with saidselectors for making character selections only *when a predeterminedinvariable number of said elements has been caused to respond to thecontrolling impulsesof a code signal, an error-indieating device, andmeans controlled solely by the integration of said controlling impulsesand oper ative in response to the reception of an excess or deficiencythereof within the time interval actuating said key solely in response"to the receipt of'a signal which lacks conformity with the .usual numberof marking and spacing elements.

9. A device in accordance with claim 8 and having an escapementmechanism operable step by-step upon receipt of each marking element ofa. code signal and means operable by said escapement mechanism to selectfor actuation the error-designating key when the number of markingimpulses received during a time interval allotted to "a code signal iseither excessive or deficient.

10. A device in accordance with claim 8 and having a relay systemoperable to count the number of marking elements of a code signal and tomake selection of the error key when the number of marking impulsesreceived during the fixed time interval allotted to a code signal iseither excessive or deficient. f

allotted to said code signal for actuating saiderror-indicating device.

3. A printing telegraph apparatus having a plurality ofde-coding.members each actuable in response to the reception of a marking elementof a code signal, and type selecting elements each selectable only uponthe actuation of a fixed normal number of said de-coding, members otherthan one-half the total number thereof. i

11-. The method of indicating the receptionlof a mutilated charactercode signal over a telegraph system by signal elements having selectingand non-selecting functions which comprises allotting an invariable timeinterval to each code signal, employing a code in which each signalpossesses an invariable ratio between the elements having selecting andnon-selecting. functions,

counting the selecting elements in each said time 4. In a printingtelegraph system, receiving apparatus having a plurality of decodingmem', .bers each actuable in response to the reception of a markingelement of a code signal, type' selecting elements each selectable onlyupon the actuation of a fixed normal number of said decoding members,means including an additional type selecting element for indicating thereception of a mutilated signal and means rendered effective uponreceipt of an abnormal number of marking impulses within a fixed timeinterval allotted to a code signal for thenactuating said additionaltype-selecting element to cause an error-designating character to beprinted in place of such character as would correspond to the signalbefore mutilation thereof. i 5. In a telegraph system, code signalreceiving means-comprising a first series of impulse-respon- 1 intervaland causing an indication to be made when there is an excess ordeficiency in said se-v lecting elements. i

, 12. In a telegraph receiving system, recording means responsive tocode signals having a uniform number of elements of a certaincharacteristic plus elements of a different characteristic, an errorindicating device, and means responsive to the receipt of a code signalhaving an' abnormal number of elements of said certain characteristicfor actuating said error indicating device, said sive devices and asecond series of devices each responsive upon the cessation, of animpulse through an associated one of said impulse-responsive devices,and circuits interconnecting the apparatus, a receiving printer havingcharacter selecting elements, de-codingmeans operable in response tosignals having a permutational arrangement of 'marking and spacingunits, the number of said markin units being in fixed ratio to thespacing units ior determining the sequence of operationof the characterselecting elements, and means operable in sole dependence upon adeparture from said fixed ratio for causing said printer to print anerror-designating character.

6. A system in accordance with claim 5 and having an, impulse countingdevice mechanically associatedwith said decoding means and-fullycontrolled thereby for, determining instances when mutilated signals arereceived.

7. A system in accordance with claim 5 and having a relay networkoperable under the full devices of the two series" in such manner thatthey act as impulse counting relays for preventing the operation of saiderror indicating device upon reception of a correct code signal.

13. In a. printing telegraph system, means responsive to characterrepresenting signals of equal length, means to decode such of saidsignals as possess a normally fixed ration between 'the number ofmarking and spacing units thereof, actuating mechanism responsive to theoperation of said decoding means to print a designated character, anderror designating means respon sive to the reception of a signalwherein. the marking-to spacing unit ratio is other than the onenormally fixed.

l4.'A' printing telegraph apparatushaving a plurality of de-codingmembers each actuable in response to the reception of a marking elementof a code signal, type selecting elements each selectable by anappropriate combination of a normally fixed number 01' said de-codingmembers', and means efiective whenever a received code signal containsan excess or deficiency of plurality of de-coding members each actuablein 5 response to the reception of a marking element of a code signal,type selecting elements each selectable by an appropriate combination of,a-

normally fixed number of said de-coding'meme bers, an error indicatingdevice,'and means eflfective whenever a received code signal contains anexcess or deficiency of marking elements with respect to said normallyfixed number for actuating said error indicating device.

16. In a printing telegraph system, a plurality of type bar selectors,means including a plurality of decoding elements cooperative with saidselectors for making character selections in response to the receptionof any one 01' a number of diflferentcode signals all of which arechar-g acterized by an invariable number of controlling units, and meanscontrolled. solely by the integration of said controlling units andoperative in response to the reception of an excess or de-- flciencythereof within the time interval allotted to a single code signal forpreventing the operation of the first said means.

.17. A telegraph receiving system comprising means responsive tocharacter representing signals oi equal length, means to decode such ofsaid signals as possess a normally iixed ratio be- '2 tween the numberof marking and spacing units thereof, apparatus under control of saiddecoding means for recording the characters represented by said signals,and a utilization device operable in response to the reception of asignal wherein the marking-to-spacing unit ratio is other than the onenormally fixed.

18. In a telegraph receiving system utilizing a fixed total number ofmarking and spacing ele-'- ments oi uniform length. and combined in afixed ratio, the method'oi diflerentiating'between such code signalswhen received, and other combinations of received signal elements, saidmethod comprising counting the eflectively received marking elements ineach combination, and producing'an error designating response to thereception of signal combinations in which the eflectlve marking elementcount denotes a departure so from said fixed ratio;

19. In an electrical system or communication. the method oi'signalreception which comprises selecting characters to be printed in responseto codesignals each original composed of a M61, termined number ofmarking elements and a predetermined number of spacing elements, all orsaid elements being of unitorm length. testing the code signals receivedby counting the number of eflective marking elements in each sig- I nalto distinguish between true code signals and mutilated code signals, andcausing an indication to be made when there is an excess or deficiencyin the number of said eflective marking element.

20. In radio telegraphy, the method or reception of uniform length codesignals the marking and spacing components of which are originally ofuniform length and are maintained in a fixed ratio for each charactercode combination, said method comprising testing the signals received byan integration oi the eflective marking elements thereof to determinethe presence of absence of said fixed ratio, and causing an indicationto be made when the absence 01' said fixed ratio is determined.

"21. In a telegraph system, receiving apparatus operative in response toincoming signals composed of groups of marking and spacing elements,said groups being of effectively equal length and containing the sametotal oi elements, each.oi said groups being coded to designate aseparate character, said receiving appa-,

ratus including means for counting the eflective marking elements ineach code combination, and means operative whenever the count indicatesa departure from a fixed normal ratio between marking and spacingelements for indicating the reception of a mutilated signal.

22. In a telegraph receiving system, the combination of receivingapparatus comprising printer type selector mechanism, means fortranslating uniform length code combination signals into actuatlons ofsaid type selector mechanism thereby to cause the printing of selectedcharacters, means for counting the 'efiectively received markingelements in each character code combination, means for distinguishingbetween a normally fixed count of such marking elements and code signalsall of which possess, as transmitted, 40

, mutilation of said signals,.and means to decode departures therefromsuch as result from the i normally fixed count when received.

23. In an electrical system or communication, the combination ofreceiving apparatus comprising means responsive to code combinationsignals each of which signals is normally composed ot. a fixed number ofmarking elements and a fixed number 01 spacing elements, printingapparatus having character selecting means responsive tothe reception01' said signals whenthey are normally composed, means for detecting thereception ofslgnals which, due to mutilation, possess an abnormal ratiobetween their eilective marking and spacing elements, and means forprinting an error indicating symbol under control of said detectingmeans.

JOHN B. MOORE.

